The present invention relates to a method of processing a silver halide photographic material. Specifically, it relates to a method of processing a silver halide photographic material, in which the amount of the waste liquid from the processing solution used is reduced or eliminated so that the method does not cause environmental pollution. Additionally, the method yields processed photographic materials having extremely stable photographic characteristics.
In continuously processing a silver halide photographic material, especially with a large-sized processing machine, a method is generally employed in the processing machine in which a replenisher having a high activity is replenished to the processing tank containing a tank solution in accordance with the amount of the photographic material processed. In the method, the tank solution overflows a so-called overflow solution in accordance with the amount of the replenisher added to the processing tank. The overflow solution is drained away from the processing system. The drained solution is recovered and treated as a waste solution. This waste solution, however, has a large environmental pollution load value. Therefore, drainage of such a waste solution is unfavorable for the protection of environment against environmental pollution or disruption. Additionally, the cost of recovery and treatment of the waste solution is significant.
Under the circumstances, heretofore, various techniques of reducing the amount of the waste solution have been investigated in this technical field. As one example, a method of removing the accumulated and excess components, if any, from the overflow solution by supplementing the solution with the deficient components followed by re-using the thus treated overflow solution as a replenishment has been investigated in various ways. The method is generally called a "regenerating method" for regenerating processing solutions and is applied to various developers, bleaching solutions and fixing solutions. In the recovering method, however, maintenance of the quality of the regenerated replenisher is extremely difficult as quality is greatly influenced by the life history of the overflow solution. Additionally, since the processing solutions need quality control by various analysis in the regenerating method, the method is practicable only in laboratories having a high-level technical capabilities. In addition to such severe labor constraints on carrying out regeneration, the quality of the regenerated replenisher is generally unstable as compared with that of a non-regenerated system replenisher. Accordingly, the method itself is extremely limited and could not be said to be popular.
On the other hand, as an example of a technique of reducing the amount of the waste solution to be drained, a method of reducing the amount of the replenisher itself to be replenished to the processing system is known. In order to reduce the amount of the replenisher, it is necessary to solve the related technical problems of how to remove the influence of the accumulated components on the processed photographic material, how to prepare a concentrated replenisher, and how to improve the stability of the processing solution being used. For instance, techniques of reducing the amount of the replenisher to a color developer have been disclosed in JP-A-61-70552 and 1-105948 (The term "JP-A" as used herein means an "unexamined published Japanese patent application".). In the proposed low-replenishment system process, if the amount of the waste solution to be drained is comparable to or less than the amount of the replenisher necessary for regeneration, then the process would be universally applicable and more desirable because no special technology would be necessary.
In particular, in accordance with the proposed process, the amount of the replenisher to be replenished to the color developer of the first bath is same as the amount of the carry-over solution (which is to be carried over to the next bath along with the photographic material being processed) while the evaporated portion is corrected by adding water to the bath. Accordingly, the process is carried out, theoretically yielding no overflowed solution during processing. That is, the process yields no waste solution during processing.
However, it has been found that the above-mentioned ultra-low-replenishment system process of yielding no waste solution during processing causes formation of an overflow solution from the color developer, or on the contrary, causes lowering of the liquid level of the processing tank and, as a result, the process could not be carried out stably. In particular, lowering of the liquid level of the processing tank directly results in fluctuation of the processing time (or shortening the processing time) which causes not only deterioration of the quality of the processed photographic material but also has a bad influence on the heater and circulation system, etc., of the processing machine. The present inventors investigated the reasons for such problems, and, as a result, have found that the problems are caused by the fluctuation of the amount of the carry-over solution per unit amount of the photographic material processed. Precisely, in the processing machine of conveying the photographic material being processed by the use of a leader belt, the amount of the carry-over solution to be carried over by the leader belt must be taken into consideration (Though depending upon the material of the leader belt and the linear velocity thereof, the amount of the carry-over solution with the leader belt is generally from 1 to 3 ml per meter of the leader belt.). However, since the leader belt is not active in the processing solution, generally no replenisher is replenished to the system during conveyance of leader belt. In this situation, the processing machine is driven and run under various conditions in laboratories. Accordingly, it has been found that the amount of the leader belt to be conveyed for processing photographic material of a unit area varies in accordance with the running condition of the processing machine as to whether the machine is run without processing photographic materials, or as to whether only one line or two lines of photographic materials are set on the leader belt. As a result, the amount of the carry-over solution varies in accordance with the various running conditions.
Therefore, in carrying out the above-mentioned ultra-low-replenishment system process, the technique of maintaining the processing solution at a constant level in the processing tank is important.